Tunisia attack: National minute's silence for UK victims
A national minute's silence will be held to remember victims of the Tunisian beach attack, David Cameron has announced.
The silence will take place on Friday 3 July at 12:00 BST, a week after the shooting which killed 38 people.
No 10 also confirmed the official UK death toll stands at 18, but it is expected to rise to around 30.
All Britons injured in the attack in Sousse will be returned to the UK within 24 hours, Downing Street said.
In a speech to the Commons, following a minute's silence held by MPs, the prime minister described the attack as "brutal and sickening".
Tunisia beach attack: The victims
The names of those killed in the attack are slowly emerging. Here's what we know so far about those who lost their lives, as well as those who are injured and missing.
Some survivors have also been speaking out about their ordeal
He confirmed the gunman was thought to have been part of a network inspired by militants from Islamic State (IS).
He said there was a team of British consular staff on the ground within hours of the attack, and a team of 50 people were currently in Tunisia helping British victims and their families.
"This is not the war between Islam and the West, which Isil [also known as Islamic State] want people to believe," he said.
"It is a generational struggle between a minority of extremists, who want hatred to flourish and the rest of us who want freedom to prosper. And together, we will prevail.
"Here in the UK, the threat level remains severe, meaning a terrorist attack is highly likely. But until we have defeated this threat, we must resolve as a country to carry on living our lives alongside."
The prime minister told the house that "four or five" terror plots had been prevented in the UK in the last few months.
US President Barack Obama offered his condolences in a phone call to Mr Cameron. A Number 10 spokesperson said they also discussed the importance of working together to tackle the threat posed by Islamist extremism.
Earlier, Home Secretary Theresa May laid flowers on the beach near Sousse where gunman Seifeddine Rezgui shot at people near the Imperial Marhaba and Bellevue hotels.
The Tunisian authorities have said they believe the 23-year-old student had help with the attack, and several people have been arrested. One of those detained is reported to be Mr Rezgui's flatmate, according to local media.
Mrs May called it "a despicable act of cruelty" but said Britain was resolved to defeat "those who would do us harm".
She also held talks with the Tunisian, German, French and Belgian interior ministers on addressing the threat from IS.
Meanwhile, an RAF C17 transport plane left Brize Norton in Oxfordshire on Monday bound for Tunisia. It will repatriate four wounded Britons - another two are also expected to return home within 24 hours.
Earlier, David Cameron told BBC Radio 4's Today programme that if families wished, British military aircraft could also help return their loved ones' bodies to the UK.
Background and analysis
- What we know so far
- Special report on Tunisia attack
- How do terrorist attacks affect tourism
- Tributes have been paid to victims in England, Wales, Scotland and Northern Ireland
Tributes are continuing to be paid to the British victims, who include three generations of the same family, university graduates and a husband who died trying to shield his wife.
Three Irish people were also killed, along with one Belgian and one German, and Tunisians are also thought to be among the dead. At least 36 people were injured.
Most identities of the British victims have not been officially released.
Mr Cameron said he was aware it was taking time to identify the victims "but these are very difficult things and we must get them right".
Analysis: Dominic Casciani, home affairs correspondent
The investigation into the Tunisia beach attack has become one of the largest counter-terrorism operations the UK has seen in a decade.
More than 600 officers and staff have been assigned to the operation because of the scale of the attack and its international nature.
In the UK, some 380 officers and staff have been meeting British tourists at airports to gather evidence. On Saturday alone, the police met passengers returning on 27 flights.
Detectives will want copies of any pictures or video from their cameras and phones that will not just record the attack but, potentially, other scenes that may help establish the lead-up to Seifeddine Rezgui opening fire.
Detectives want to build as complete a picture as possible of what happened and they are appealing to anyone who was in Sousse around the time of the attack to get in touch.
Holiday firms Thomson and First Choice announced they had cancelled all their holidays to Tunisia which leave on or before Thursday 9 July. Customers can receive a full refund or choose an alternative destination free of charge.
Around 10,000 British tourists have flown home from Tunisia since Friday's attack, according to the Association of British Travel Agents (ABTA).
Tour companies have laid on extra flights to bring home the people who wanted to cut their holiday short.
Thomas Cook said it has brought back around 1,500 customers on four repatriation flights. Three left over the weekend and one left on Monday.
Analysis: Iain Watson, BBC political correspondent
David Cameron's first priority was to convince people he had a grip of the current crisis - with staff sent to help victims and their families in Tunisia, RAF planes deployed to take home the deceased, and survivors being helped to return to the UK.
His attack on IS's "poisonous narrative" was always going to bring plaudits from his fellow politicians. But the political territory then got a bit trickier to negotiate.
His diagnosis of the problem of radicalisation wasn't controversial but the consensus became strained when the prime minister suggested a cure.
He effectively ruled out British "boots on the ground" in Iraq and Syria and also talked of bringing forward a bill to undermine IS's modern methods of communication.
He didn't, however, repeat his manifesto commitment to deny those with extremist views access to the internet.
Tackling those who don't condone violence but whose views might influence impressionable young people is likely to raise questions about free speech, not just from political opponents but from some in his own party.
The prime minister chaired another meeting of the emergency committee Cobra on Monday morning.
Present at the meeting were the foreign and transport secretaries, representatives from the Metropolitan Police and intelligence agencies, as well as a Home Office minister. There were video links to Tunisia and the Scottish government.
The Tunisian government has brought in increased security measures, and the country's Interior Minister Mohamed Gharsalli said 1,000 troops would now be deployed to protect the country's beach resorts.
Meanwhile, the Foreign Office has updated its travel advice to warn that further terrorist attacks in Tunisia are possible, and urged people to be vigilant.
A major exercise is also due to take place in London "over the next two days" to ensure the UK is prepared to deal with a "serious terrorist attack", Mr Cameron has said.
The exercise had been planned in the wake of the Charlie Hebdo magazine murders in Paris in January.
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